//////////////////////////////////////////////////////////////////////////////////
//   Copyright 2011   Mark Price     mark at epickrram.com                      //
//                                                                              //
//   Licensed under the Apache License, Version 2.0 (the "License");            //
//   you may not use this file except in compliance with the License.           //
//   You may obtain a copy of the License at                                    //
//                                                                              //
//       http://www.apache.org/licenses/LICENSE-2.0                             //
//                                                                              //
//   Unless required by applicable law or agreed to in writing, software        //
//   distributed under the License is distributed on an "AS IS" BASIS,          //
//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   //
//   See the License for the specific language governing permissions and        //
//   limitations under the License.                                             //
//////////////////////////////////////////////////////////////////////////////////

package com.epickrram.freewheel.util;

import java.util.concurrent.ConcurrentMap;

public final class ConcurrentMapIdiom
{
    private ConcurrentMapIdiom() {}

    public static <K, V> V getOrCreateFromConcurrentMap(final ConcurrentMap<K, V> map,
                                                        final Creator<V> creator, final K key)
    {
        if(map.containsKey(key))
        {
            return map.get(key);
        }
        V value = creator.create();
        final V existing = map.putIfAbsent(key, value);
        if(existing != null)
        {
            value = existing;
        }
        return value;
    }
}